Coke is not a byproduct of petroleum. It is a solid residue remaining after certain types of bituminous coals are heated to a high temperature out of contact with air until substantially all of the volatile constituents have been driven off. The residue is chiefly carbon, with minor amounts of hydrogen, nitrogen, sulphur and oxygen. Also present in coke is the mineral matter in the original coal, chemically altered and decomposed during the coking process. 90. Polar bears are supremely adapted